It is known that vinyl esters of saturated aliphatic monocarboxylic acids whose carboxyl groups are attached to a tertiary and/or quaternary carbon atom can be copolymerized in an emulsion in water with other ethylenically unsaturated monomers such as vinyl acetate, vinyl chloride, and esters of alpha-beta ethylenically unsaturated acids, preferably in the presence of a small amount of an alpha-beta ethylenically unsaturated acid, in the presence of free-radical supplying polymerization initiators, whereby various types of emulsifying or stabilizing agents for emulsions can be used. It is also known that such copolymer emulsions can be used advantageously in latex paints on many types of substrates, such as wood, stone, concrete, and asbestos cement, in combination with usual pigments for latex paints. So, for example, their use for exterior decoration of buildings is well known. Coats obtained with such paints are highly resistant to chemical and mechanical influences; they have low water absorption, and they stand up very well to the action of alkaline substances, such as concrete, or alkaline detergents; when applied to substrates outlined above they are also highly resistant to wet brushing with water or with detergents.
For further discussion relevant to the preparation of such vinyl ester latices see British Pat. No. 933,470; U.S. Pat. No. 3,186,974; U.S. Pat. No. 3,287,300 and U.S. Pat. No. 3,294,727, among many other patents.
Recently, however, a new field of application of latex paints has become of interest, namely, the application on glossy, usually old, solvent-borne paint films, in particular domestic paint films. The application on this substrate requires advanced adhesion characteristics, in particular against the usual wet-cleaning with cloth, sponge or wash-leather to which such paints are often subjected in household applications.
The present invention therefore provides a modification for vinyl ester latices as hereinbefore described, by which an improvement with respect to the aforesaid application on existing paint films is obtained. The modification comprises the copolymerization of a small amount of a glycidyl ester of an alpha-beta ethylenically unsaturated acid, followed by reaction with a small amount of ammonia. By the use of these additives the final copolymer product contains a small amount (as restricted by the amount of glycidyl ester and the amount of ammonia) of hydroxyaminopropyl ester groups.